I’m in the process of looking for a new job and have been doing some research online. It seems that a lot of people send out generic resumes to a ton of companies. I’m in the mobile development field and I’m trying to figure out if this has any legitimate benefits.

I can smell a generic CV a mile off and usually don't even bother to read it. People who sift through applications want to know that the person applying has selected their company for a reason e.g. interesting product, lots of relevant experience in the sector and so on. If you scatter bomb every man and his dog with your CV, it looks like you are desperate and have not given your future career much thought. As Vishal says, it's all about quality so you should tailor your CV (ideally to a specific role) or at the very least to the company you are applying to if they are not advertising a vacancy.

I also recommend always sending a covering email so you can reveal a bit more of your personality!